1. Field of Invention
The present invention relates to an element driving device for driving a plurality of driven elements and a method of manufacturing the same, and specifically to an electro-optical device which uses, as the driven elements, electro-optical elements for converting an electrical action into an optical action, and a method of manufacturing the same. In addition, the present invention relates to an element substrate suitable for the element driving device and the electro-optical device, and to an electronic apparatus including the electro-optical device and the element driving device.
2. Description of Related Art
It has been suggested that electro-optical elements for converting an electrical action into an optical action be used as display devices of various types of electronic apparatuses, such as mobile phones or PDAs (Personal Digital Assistants). Typical examples of such display devices include an organic EL display device using an organic EL material as the electro-optical element, or a liquid crystal display device using liquid crystal as the electro-optical element.
In these display devices, every pixel, a minimum unit for display, has a pixel circuit. This pixel circuit is a circuit for controlling the current or voltage supplied to the electro-optical element. Each pixel circuit, as disclosed in paragraph No. 0013 and paragraph No. 0014 of Japanese Unexamined Patent Application Publication No. 9-146477, includes a driving element formed on a silicon substrate.
In order to improve the quality of display in such display devices, it is desirable that the electrical characteristics of the pixel circuit be uniform over all pixels. However, for low-temperature polysilicon, variation in characteristics can easily occur in re-crystallization and, in addition, crystal defects may occur. Due to such variation and defects, for a display device using thin-film transistors including low-temperature polysilicon, it is very difficult to make the electrical characteristics of the pixel circuits uniform over all pixels. Specifically, if the number of pixels increases to improve the resolution of the display image or to increase the size of the screen, the possibility to generate the variation in characteristics of the respective pixel circuits may increase. Thus, the deterioration of the display quality may become more serious.
The present invention is conceived in view of such problems, and it is an object of the present invention to suppress variation in characteristics of active elements in a circuit for driving driven elements, such as electro-optical elements, thus improving performance, functionality, and the degree of integration of the circuit.